Computer Facial Animation - Excercises

Pre-reading excercises

1. Students are given pictures of human faces and try to guess what emotions they show.
2. What is the number of facial muscles?
   • 48
3. Why are facial expressions so important in our lives?
   • Gestures and facial expressions in general mean more than words or sentences.
4. Where can facial animations be used?
   • In cartoons, 3D rendered films (like Toy Story, Shrek) and in computer games. Facial animation is constantly improving and in a couple of years it will be hard to distinguish between a real actor and a virtual one.
5. What is the rendering process in computer graphics? What is the motion capture technique?
   • Rendering: all of the methods used to make a picture using a computer. It involves maths calculations, data loading and so on.
   • Motion capture is a technique used to obtain realistic animated movement. An actor wears a special outfit with a number of sensors. When he moves, a computer captures all the necessary movement data.

Comprehension questions

1. How would you define facial animation?
   • Area of computer graphics that encapsulates models and techniques for generating and animating images of the human head and face.
2. What is FACS?
   • Facial Action Coding System - defines 64 basic facial Action Units which represent primitive movements of muscles in actions, e.g. raising brows, talking.
3. What was Michael Jackson’s contribution to computer animation?
   • His video of the song “Black Or White” was the first to use image morphing animation. The video showed a lot of human faces which are morphed from one to another.
4. What can 2D animation be based on: images from still photography or sequences of video?
   • Both. There are methods for animating still images and others for animating sequences of video.
5. What is the most realistic method of 3D animation? What makes it so good?
   • The skeleton-muscle system. It is so effective because the method tries to imitate human head muscles, skin and bones. It is very complicated to build a model consistent with this method but the effects are breathtaking. It cannot be used in computer games or on-line animation because of its complexity but is great for high-budget films.
6. How does motion capture work?
   • The subject is fitted with reflectors or sources that precisely determine its position in space. Every movement of the sensor is recorded and then retraced on the model. It’s very realistic but there are also some disadvantages like vibrations of sensors causing disturbances.
7. How are visemes used in speech animation?
   • Visemes are movements of lips and mouth muscles performed during speaking. Visemes are used to represent key poses in observed speech. (position of lips, jaw, tongue).

Possible topics for discussion

1. How do you see the future of facial animation?
2. Think of your favourite computer animated character. Try to name the techniques used to create it.
3. Is it probable that facial animation will achieve such a level of sophistication that it will be impossible to distinguish real faces from virtual ones?

Possible difficulties

The text contains professional vocabulary items. Some of them are explained.